1. Field of the Invention
This invention relates to a disk recording device for recording data such as muscial information on a recordable disk on which absolute addresses have been previously recorded. This invention is applied to a plyaing device for recordable and reproducible compact disks or CDs.
2. Description of the Prior Art
Read only memory type disk playing devices such as CD players for exclusively reproducing compact disks or CDs wherein musical or audio signals are digitized and recorded on optical disks have been utilized. In these compact disks, all the musical tones involved are successively recorded, and when reproduction of one tune is over, said CD players usually continue reproducing operation of the next tune so that successive reproduction takes place.
Known CD players are exclusive for reproduction, so it has been evolved to provide a disk system which uses an opto-magnetic disk made of a rewritable opto-magnetic recording medium for enabling information recording and reproduction and which retains superior compatability with the compact disks.
In a recordable disk 1 employed in such disk system, as shown in FIG. 1 of the accompanying drawings, there are formed spiral pre-grooves 2 each of which is .lambda./8 in depth (.lambda. indicates the wavelength of a laser beam for recording information). In each land section 3 between the pre-grooves 2, a pre-recorded area 4 on which pits of .lambda./4 in depth are recorded in the circumferential direction presenting uneven shapes and a data record area 5 where the opto-magnetic recording is performed are alternately provided at regular intervals. Also in the recordable disk 1, there is provided a lead-in section 7 on the inner circumference of a program area 6 where musical information is recorded, and so-called TOC (table of contents) information indicating the recorded contents on the program area6 are recorded in the lead-in section 7. With reference to FIG. 2, one frame of a data format standardized in the compact disks adopting EFM (Eight to Fourteen Modulation) consists of 588 channel bits, with 24-bit synchronous signals, 14-bit (one symbol) subcodes, 14.times.32-bit (32 symbols) data such as musical information with parity, and 3-bit margin bits provided between the respective symbols. Among these modulation data, above-stated synchronous signals and subcodes are recorded on the pre-recorded area 4 of the recordable disk 1 presenting uneven shapes produced by a so-called embossing finish, and are provided with absolute timing information (absolute address) as the subcode from a starting position on the program area 6.
The disk system utilizing such recordable disk 1 controls for example rotation of the disk at Constant Linear Velocity (CLV) by using the absolute address reproduced from the pre-recorded area 4, and performs information recording and reproduction with the standardized data format for the compact disks.
It is to be noted that all the tunes are not necessarily recorded in succession on the disk in such disk system retaining superior compactability to said compact disks. That is, an unrecorded part may appear between a first tune and a second tune, for example. In such a case, if successive reproduction is performed, a silent part may be continuously reproduced during the interval after the termination of the first tune and before the start of the second tune. Also in case a so-called superposed recording, namely, recording a new tune to an already recorded section, if a part of the originally recorded tune remains after the newly recorded tune, such part is also reproduced during reproduction. Besides, in case further recording is performed in a recordable area including an unrecorded area or unnecessarily recorded area using a disk on which several tunes have already been recorded, it is necessary to determine if such recordable area is spacious or long enough for newly proposed recording. In such a case, a complicated operation for seeking a starting part of the already recorded tune so as to calculate the recorded time is required. When said unrecorded and/or unnecessarily recorded areas are present dispersedly in the plural sections, tremendous steps are required for determining the recordable area needed for recording a new tune.